The rats are infected by the plague and they are on a ship, and wherever that went, it made the plague spread.
The rats are spreading which means the plague is spreading and because of that many people are dying.
BRING OUT THE DEAD
Because so many people died from the plague, there were very few people left to do their jobs which affected and made a decline to feudalism.
seal the Carta NOW!
The king was forced to sign the Magna Carta.
Because he signed the Magna Carta, he had the same rules as everyone else which made a decline of feudalism. And because of that, almost everyone even peasants rose in wealth, not needing to work which is also caused the fall.
SILK TO COME
Instead of peasants working in the manor, the peasants made there own bussiness and sold things of their own instead of working at the manor which made a decline in feudalism.